U.S. patent number 7,386,386 [Application Number 11/264,964] was granted by the patent office on 2008-06-10 for driving control apparatus.
This patent grant is currently assigned to Honda Motor Co., Ltd.. Invention is credited to Toshiaki Arai, Hisaya Izawa, Makoto Matsumoto, Tadayoshi Okada.
United States Patent |
7,386,386 |
Arai , et al. |
June 10, 2008 |
Driving control apparatus
Abstract
A driving control apparatus comprising: an detecting device that
detects objects; a preceding vehicle determining device that
determines a preceding vehicle; a driving control device that
executes a driving control; a control start intention detection
device that detects an intention of a driver to start the control;
and a control start intention detection device that detects an
intention of a driver to start the follow-up control or the stop
hold control, wherein the control state determination device sets
to the follow-up control state when the preceding vehicle is
detected by the preceding vehicle detection device and when the
intention is detected, and sets to the stop hold state when the
intention is detected while the vehicle is substantially in the
stopped and no object is detected by the object detection
device.
Inventors: |
Arai; Toshiaki (Utsunomiya,
JP), Okada; Tadayoshi (Shioya-gun, JP),
Izawa; Hisaya (Utsunomiya, JP), Matsumoto; Makoto
(Utsunomiya, JP) |
Assignee: |
Honda Motor Co., Ltd. (Tokyo,
JP)
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Family
ID: |
36217416 |
Appl.
No.: |
11/264,964 |
Filed: |
November 1, 2005 |
Prior Publication Data
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Document
Identifier |
Publication Date |
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US 20060095194 A1 |
May 4, 2006 |
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Foreign Application Priority Data
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Nov 4, 2004 [JP] |
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P2004-320401 |
Oct 13, 2005 [JP] |
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P2005-298563 |
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Current U.S.
Class: |
701/96; 340/435;
340/436; 340/903; 342/455; 701/301; 701/466 |
Current CPC
Class: |
B60T
7/12 (20130101); B60W 30/16 (20130101); B60W
30/17 (20130101); B60W 30/18018 (20130101) |
Current International
Class: |
B60T
7/12 (20060101) |
Field of
Search: |
;701/23,28,1,93,96,205,301 ;340/435,436,903 ;342/70,455
;180/170,179 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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06-171482 |
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Jun 1994 |
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JP |
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3194305 |
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Jun 1994 |
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JP |
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Primary Examiner: Jeangla; Gertrude Arthur
Attorney, Agent or Firm: O'Melveny & Myers LLP
Claims
What is claimed is:
1. A driving control apparatus comprising: a vehicle speed sensor
that detects a traveling speed of a vehicle; an object detecting
device that is installed in the vehicle and is capable of detecting
objects that are present in a direction in which the vehicle
travels; a preceding vehicle determining device that determines a
preceding vehicle which the vehicle is to follow among the detected
objects; a target inter-vehicle distance determination device that
determines a target inter-vehicle distance between the vehicle and
the preceding vehicle; a target vehicle speed determining device
that determines a target vehicle speed of the vehicle based on a
signal from the object detecting device and the target
inter-vehicle distance determined; a driving control device that
executes a driving control on the vehicle based on the determined
target vehicle speed; a control state determination device that
sets the control state of the vehicle to one of a follow-up control
state in which the vehicle is made to travel following at least the
preceding vehicle and a stop hold state in which the vehicle is
maintained in a stopped state; and a control start intention
detection device that detects an intention of a driver to start the
follow-up control or the stop hold control, wherein the control
state determination device sets the control state of the vehicle to
the follow-up control state when the preceding vehicle is detected
by the preceding vehicle determining device and when the intention
of the driver to start the follow-up control or the stop hold
control is detected by the control start intention detection
device, and sets the control state of the vehicle to the stop hold
state when the intention of the driver to start the follow-up
control or the stop hold control is detected by the control start
intention detection device while the vehicle is substantially in
the stopped state and no object is detected by the object detection
device.
2. The driving control apparatus according to claim 1, wherein the
control start intention detection device detects the intention of
the driver to start the follow-up control or the stop hold control
based on a signal from a switch provided in the vicinity of a
steering wheel.
3. The driving control apparatus according to claim 1, further
comprising a time counting device that starts counting an elapsed
time between when the intention of the driver to start the
follow-up control or the stop hold control is detected and when the
preceding vehicle is detected, wherein the control state
determination device changes the control state of the vehicle from
the stop hold state to the follow-up control state when the elapsed
time that is counted by the time counting device is within a
predetermined time period.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a driving control apparatus that
executes driving control of a vehicle by selecting a vehicle that
is traveling in front of the vehicle so that it can follow that
vehicle. More specifically, the present invention relates to a
driving control apparatus that executes a low speed following (LSF)
in which the vehicle can be started or stopped following the
preceding vehicle in a relatively low vehicle speed region.
Priority is claimed on Japanese Patent Application No. 2004-320401,
filed Nov. 4, 2004 and Japanese Patent Application No. 2005-298563,
filed Oct. 13, 2005, the contents of which is incorporated herein
by reference.
2. Description of the Related Art
In recent years, various types of driving control apparatuses have
been developed which are aimed at reducing the driver's work load
in operating the vehicle.
One type of such apparatuses is a driving control apparatus that
executes a low-speed follow-up control that controls a driving
state of a vehicle such that a predetermined inter-vehicle distance
is maintained between the vehicle and a preceding vehicle when the
vehicle is traveling at a low speed (including when the vehicle is
stopped).
For example, Japanese Patent No. 3194305 discloses a technique in
which when a vehicle is stopped at the front at a red light at an
intersection or at the front at a railroad crossing, if a brake
pedal is depressed and the vehicle speed is zero, the stopped state
is maintained by a brake operating device. With this technique,
even when the inter-vehicle distance to the preceding vehicle is
increased, the brake hold state is not canceled. The brake hold
state is canceled when the inter-vehicle distance to the preceding
vehicle is equal to or less than a predetermined value and when a
relative speed with respect to the preceding vehicle is a positive
value.
Millimeter-wave radar apparatuses are widely used as devices for
detecting a preceding vehicle. However, these radar apparatuses may
fail to detect an object which is at a shorter distance than the
detectable distance since the time interval between the time when
the radar transmits electromagnetic waves and the time when the
waves reflected by the object are received is short. Therefore,
even when a vehicle is preceding the vehicle, the LSF control is
not executed since the preceding vehicle is not detected when the
distance from the preceding vehicle is very short, or when a
pedestrian passes between the vehicles, for example. As a result,
the driver is required to operate the brake manually and
continuously in order to maintain the vehicle in the stopped state,
which is an inconvenience to the driver. In addition, the driver
may feel discomfort since a follow-up control is cancelled even
when the vehicle is preceding the vehicle.
Accordingly, the present invention is directed to provide a driving
control apparatus that is capable of continuing an execution of an
LSF control even when no preceding vehicle is detected in order to
enhance the convenience without discomforting the driver.
SUMMARY OF THE INVENTION
A first aspect of the present invention is a driving control
apparatus comprising: a vehicle speed sensor that detects a
traveling speed of a vehicle; an object detecting device that is
installed in the vehicle and is capable of detecting objects that
are present in a direction in which the vehicle travels; a
preceding vehicle determining device that determines a preceding
vehicle which the vehicle is to follow among the detected objects;
a target inter-vehicle distance determination device that
determines a target inter-vehicle distance between the vehicle and
the preceding vehicle; a target vehicle speed determining device
that determines a target vehicle speed of the vehicle based on a
signal from the object detecting device and the target
inter-vehicle distance determined; a driving control device that
executes a driving control on the vehicle based on the determined
target vehicle speed; a control state determination device that
sets the control state of the vehicle to one of a follow-up control
state in which the vehicle is made to travel following at least the
preceding vehicle and a stop hold state in which the vehicle is
maintained in a stopped state; and a control start intention
detection device that detects an intention of a driver to start the
follow-up control or the stop hold control, wherein the control
state determination device sets the control state of the vehicle to
the follow-up control state when the preceding vehicle is detected
by the preceding vehicle determining device and when the intention
of the driver to start the follow-up control or the stop hold
control is detected by the control start intention detection
device, and sets the control state of the vehicle to the stop hold
state when the intention of the driver to start the follow-up
control or the stop hold control is detected by the control start
intention detection device while the vehicle is substantially in
the stopped and no object is detected by the object detection
device.
In a second aspect of the present invention, the control start
intention detection device may detect the intention of the driver
to start the follow-up control or the stop hold control based on a
signal from a switch provided in the vicinity of a steering
wheel.
In a third aspect of the present invention, a time counting device
that starts counting an elapsed time between when the intention of
the driver to start the follow-up control or the stop hold control
is detected and when the preceding vehicle is detected may be
provided, and the control state determination device may change the
control state of the vehicle from the stop hold state to the
follow-up control state when the elapsed time that is counted by
the time counting device is within a predetermined time period.
According to the first aspect of the present invention, even if no
object is detected by the object detection device, the stop hold
state is set by the control state determination device when the
vehicle is substantially in the stopped state and when the
intention of the driver to start the follow-up control or the stop
hold control is detected by the control start intention detection
device. As a result, the stop hold state is set even when no
preceding vehicle is detected due to the detection limit of the
object detection device. Accordingly, it is possible to maintain
the vehicle in the stopped state even when the driver stops
operating the brake pedal. Furthermore, the discomfort that the
driver may feel when a follow-up control is cancelled even when the
preceding vehicle is present in front of the vehicle is eliminated.
Furthermore, the control state of the vehicle is set to the
follow-up control state when the intention of the driver to start
the follow-up control or the stop hold control is detected by the
control start intention detection device after the preceding
vehicle has started and the preceding vehicle can be detected by
the object detection device. Thus, it is possible to smoothly
switch a control mode to a control state in which the vehicle is
made to follows the preceding vehicle thereby reducing the driver's
load in carrying out driving operations. As described herein, the
term "a vehicle is substantially stopped" means that the vehicle
may be completely stopped, or the vehicle is traveling at a speed
at which the vehicle can be regarded as being stopped (for example,
at several kilometers per hour or less).
According to the second aspect of the present invention, since the
control start intention detection device detects the intention of
the driver to start the follow-up control or the stop hold control
based on a signal from the switch provided in the vicinity of a
steering wheel, the driver can make a control operation using the
switch provided in the vicinity of the vehicle. Thus, improved
usability allows the driver to carry out driving operations without
giving any stress.
According to the third aspect of the present invention, it is
possible to change the control state of the vehicle to the
follow-up control state when the elapsed time that is counted by
the time counting device is within a predetermined time period
since the intention to start the follow-up control or the stop hold
control has been detected. Thus, it is possible to start the
follow-up control even in the above-described situation, thereby
increasing the convenience.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a perspective view of a vehicle that includes a follow-up
driving control apparatus according to an embodiment of the present
invention;
FIG. 2 is block diagram illustrating the configuration of the
follow-up driving control apparatus shown in FIG. 1;
FIG. 3 illustrates an exemplary layout of a start/stop switch, a
control start switch, a cancel switch, and an inter-vehicle
distance set switch of the follow-up driving control apparatus
shown in FIG. 1;
FIG. 4 is a state transition diagram of a driving control executed
by a control state determination device in the follow-up driving
control apparatus shown in FIG. 1; and
FIG. 5 is a flowchart showing an operation to determine whether to
start an LSF of the follow-up driving control apparatus shown in
FIG. 1.
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, a driving control apparatus according to an embodiment
of the present invention will be described with reference to the
drawings.
Configuration of Apparatus
FIG. 1 is a perspective view of a vehicle 1 that includes a
follow-up driving control apparatus according to an embodiment of
the present invention, and FIG. 2 is block diagram showing the
configuration of the follow-up driving control apparatus shown in
FIG. 1.
The driving control apparatus according to the present embodiment
is constructed as a millimeter wave radar integrated ECU
(Electronic Control Unit) 2. The vehicle 1 includes a vehicle speed
sensor 3 that detects the vehicle speed of the vehicle 1, and a yaw
rate sensor 4 that detects the yaw rate of the vehicle 1. The
detected vehicle speed and the yaw rate are sent to the millimeter
wave radar integrated ECU2 (driving control apparatus).
Furthermore, a throttle actuator 5 that operates the throttle of an
engine of the vehicle 1 by means of fluid pressure and electricity
and a brake actuator 6 that similarly operates brakes of the
vehicle 1 by fluid pressure and electricity are provided in the
vehicle 1.
A brake lamp 7 that indicates the operating state of the brakes of
the vehicle 1 is provided in the rear of the vehicle 1.
Furthermore, in the vicinity of the cockpit of the vehicle 1, a
display device 8, and a buzzer 9 that notify the control status of
the driving control apparatus to the driver are provided. In the
vicinity of a steering wheel 31, switches 10 for receiving driving
operations from the driver to be sent to the driving control
apparatus are provided.
Here, the millimeter wave radar integrated ECU 2 (follow-up driving
control apparatus) will be explained in detail with reference to
FIG. 2. Reference numeral 11 denotes a radar apparatus of the
millimeter wave radar integrated ECU 2, provided in the front of
the vehicle 1. The radar apparatus 11 transmits a radar wave around
the vehicle 1, and receives a reflected wave of the radar wave
reflected by an object. The radar apparatus 11 uses the received
reflected wave to detect objects that are present in front of the
vehicle 1.
The follow-up driving control apparatus of the present embodiment
also includes processing devices embodied in the ECU portion of the
millimeter wave radar integrated ECU 2 having a CPU (central
processing device). Such processing devices include a notification
processing device 12, a throttle control device 13, a brake control
device 14, a brake fluid pressure determination device 15, a target
determination device 16, a control state determination device 17, a
target inter-vehicle distance determination device 18, and a target
vehicle speed determination device 19.
The notification processing device 12 is a processing device that
notifies the control status of the follow-up driving control
apparatus to the driver by means of the display device 8 and/or the
buzzer 9 in the vicinity of the cockpit.
The throttle control device 13 is a processing device that controls
the throttle actuator 5 that sets the degree of throttle opening
(throttle position) for operating the throttle of the engine of the
vehicle 1.
The brake control device 14 is a processing device that controls
the brake actuator 6 for operating the brakes of the vehicle 1. The
control by the brake control device 14 is executed based on the
target fluid pressure (hydraulic pressure) of the brake fluid that
is determined by the brake fluid pressure determination device 15.
The turning on and off of the brake lamp 7 that is installed in the
rear of the vehicle 1 is controlled based on the target fluid
pressure of the brake fluid that is determined by the brake fluid
pressure determination device 15, or the actual fluid pressure.
The target determination device 16 is a processing device that
processes information on objects that are present ahead of the
vehicle 1 which is detected by the radar apparatus 11. The target
determination device 16 includes a driving route calculation device
that calculates the driving route of the vehicle 1 based on the
vehicle speed determined by the vehicle speed sensor 3 or the yaw
rate determined by the yaw rate sensor 4. The target determination
device 16 also includes a preceding vehicle determination
processing device that detects a preceding vehicle that the vehicle
1 follows based on the calculated vehicle driving route and
information, which is received from the radar apparatus 11, on the
objects that are detected ahead of the vehicle 1, and calculates
the object information on the detected preceding vehicle and the
distance and the relative speed between the preceding vehicle and
the vehicle 1.
Furthermore, also provided is a preceding vehicle start detection
device that determines whether or not the preceding vehicle has
been started from the stopped state based on the calculated object
information in order to detect starting of the preceding
vehicle.
For example, the preceding vehicle determination processing device
determines the radius (R) of a corner of the road on which the
vehicle 1 is traveling, and determines the route of the vehicle by
dividing the traveling speed of the vehicle 1 by the yaw rate of
the vehicle 1. The preceding vehicle determination processing
device then recognizes a vehicle on an extension of the route of
the vehicle as a preceding vehicle. The preceding vehicle
determination processing device detects static objects, such as a
reflector and a white line along the sides of a traffic lane, and
distinguishes a preceding vehicle in the traffic lane along which
the vehicle 1 is traveling from vehicles on adjacent traffic lanes.
When the vehicle 1 stops, the preceding vehicle determination
processing device distinguishes the preceding vehicle from other
vehicles by utilizing the route of the vehicle until the vehicle
stops.
The control state determination device 17 is a processing device
that executes driving control based on a signal from switches 10
(including a start/stop switch 25 for receiving a request to start
or stop the vehicle 1 from the driver, or a control start switch 26
for receiving a request to start the follow-up control, or a cancel
switch 27 for receiving a request to cancel the follow-up control)
that are configured to input driving operations from the driver,
and the object information that it is received from the target
determination device 16. The control state determination device 17
controls the driving control of the vehicle 1 by state transition
among states A: OFF, B: FOLLOW-UP, and C: STOP HOLD and notifies a
control state to the driver by means of the notification processing
device 12. The state transition of the driving control of the
vehicle 1 in the control state determination device 17 will be
described in detail later.
The target inter-vehicle distance determination device 18 is a
processing device that determines a target inter-vehicle distance
between the vehicle 1 and the preceding vehicle based on operation
of an inter-vehicle distance set switch 28, i.e., one of the
switches 10 that are configured to receive driving operations from
the driver, the target inter-vehicle distance being controlled by
the follow-up driving control apparatus of the present embodiment.
The target vehicle speed determination device 19 calculates an
optimal traveling speed of the vehicle 1 based on the control state
determined by the control state determination device 17 and the
determined target inter-vehicle distance determined by the target
inter-vehicle distance determination device 18, and controls the
throttle control device 13 and the brake fluid pressure
determination device 15 so that the vehicle 1 travels at this
target vehicle speed.
More specifically, when the target vehicle speed is greater than
the current traveling speed of the vehicle 1, the target vehicle
speed determination device 19 instructs the throttle actuator 5 to
increase the degree of the throttle opening that is output by the
throttle control device 13 so that the number of revolutions of the
engine is increased to accelerate the vehicle. In contrast, when
the target vehicle speed is lower than the current traveling speed
of the vehicle 1, the target vehicle speed determination device 19
instructs the brake actuator 6 to increase the target fluid
pressure of the brake fluid that is output by the brake fluid
pressure determination device 15 so that the brake control device
14 applies the brakes.
The vehicle 1 of this embodiment includes the following functions:
low-speed follow-up, stop hold, preceding vehicle start
notification, cancellation, preceding vehicle switching, stop hold
continue, automatic cancellation, and alert functions. Descriptions
of each of the functions are listed in Table 1.
TABLE-US-00001 TABLE 1 No. Function Description 1 Low-Speed Drive
the vehicle following the preceding Follow-Up vehicle when the
CONTROL START SW is depressed at the vehicle speed region of 40
km/h or lower 2 Stop Hold Stop the vehicle in response to the
preceding vehicle's stopping; maintain the stopped state afterward
3 Preceding Notify a start of preceding vehicle by Vehicle Start
means of visual and audio indications Notification 4 Cancellation A
brake operation is cancelled when the START SW is depressed or the
accelerator pedal is depressed, and following is restarted 5
Preceding Follow a new target when another target Vehicle is locked
by means of an interruption or Switching the like 6 Stop Hold When
the radar misses the preceding Continue vehicle, the stop hold is
continued and a brake is not cancelled 7 Automatic When the radar
misses the preceding Cancellation vehicle, the control is cancelled
after some time interval 8 Alert Notify the driver by means of
visual and audio indications that a brake operation by the driver
is required
FIG. 3 illustrates an exemplary layout of the start/stop switch 25,
the control start switch 26, the cancel switch 27, and the
inter-vehicle distance set switch 28 described above. These
switches are positioned near the steering wheel 31 for the
convenience of the driver. The start/stop switch 25, the control
start switch 26, the cancel switch 27, and the inter-vehicle
distance set switch 28 may function as operating switches of a
cruise control apparatus that is equipped in the vehicle 1.
Control State Transition
The state transition of driving control executed by the control
state determination device 17 will be described with reference to
the drawings.
FIG. 4 is a state transition diagram of driving control states in
the control state determination device 17.
In FIG. 4, as described previously, the driving control states
include three states: A: OFF, B: FOLLOW-UP, and C: STOP HOLD. Among
them, in the A: OFF state, the driving control by the follow-up
driving control apparatus is not executed. In the B: FOLLOW-UP
state, the driving control by the follow-up driving control
apparatus is executed. In the C: STOP HOLD state, after the
preceding vehicle that the vehicle 1 follows stops, the vehicle 1
stops following the preceding vehicle, and remains stopped.
The control state determination device 17 causes a driving control
state to be transitioned in response to various inputs described
below, as shown in FIG. 4.
First, when the driving control state is in the A: OFF state, if
the driver depresses the control start switch 26 while the
preceding vehicle that the vehicle 1 follows is detected, the
control state determination device 17 transitions the driving
control state from the A: OFF state to the B: FOLLOW-UP state
(state transition SE1).
In contrast, when the driving control state is in the B: FOLLOW-UP
state, if the preceding vehicle that the vehicle 1 follows is
missed or if the driver depresses the cancel switch 27 or presses
the brake pedal, the control state determination device 17
transitions the driving control state from the B: FOLLOW-UP state
to the A: OFF state (state transition SE2).
Furthermore, when the driving control state is in the B: FOLLOW-UP
state, if the preceding vehicle is stopped and the vehicle 1 stops
in a predetermined position behind the preceding vehicle, the
control state determination device 17 transitions the driving
control state from the B: FOLLOW-UP state to the C: STOP HOLD state
(state transition SE3).
Furthermore, when the driving control state is in the C: STOP HOLD
state, if the driver depresses the start/stop switch 25 or presses
the accelerator pedal, the control state determination device 17
transitions the driving control state from the C: STOP HOLD state
to the B: FOLLOW-UP state (state transition SE4). That is, a
depression of the start/stop switch 25 when the state of the
driving control is in the C: STOP HOLD state represents an
intention of the driver to start the vehicle.
In contrast, if the driver depresses the start/stop switch 25
within a predetermined time after the driving control state
transitions from the C: STOP HOLD state to the B: FOLLOW-UP state,
the control state determination device 17 transitions the driving
control state from the B: FOLLOW-UP state to the C: STOP HOLD state
(state transition SE5). That is, a depression of the start/stop
switch 25 in this case represents an intention of the driver to
stop the vehicle.
Furthermore, if the preceding vehicle does not start within a
predetermined time after the driving control state transitions from
the C: STOP HOLD state to the B: FOLLOW-UP state, the control state
determination device 17 transitions the driving control state from
the B: FOLLOW-UP state to the C: STOP HOLD state (state transition
SE6).
Furthermore, when the driving control state is in the A: OFF state,
if the driver depresses the control start switch 26 when the
preceding vehicle that the vehicle 1 follows is stopped and the
vehicle 1 stops behind the preceding vehicle, the control state
determination device 17 transitions the driving control state
directly from the A: OFF state to the C: STOP HOLD state (state
transition SE7).
When the driving control state is in the C: STOP HOLD state, if the
driver depresses the cancel switch 27 or presses the brake pedal,
the control state determination device 17 transitions the driving
control state directly from the C: STOP HOLD state to the A: OFF
state (state transition SE8).
If a start of the preceding vehicle is detected when the driving
control state is in the C: STOP HOLD state, the control state
determination device 17 notifies the driver of the start of the
preceding vehicle by means of the notification processing device 12
(state transition SE9).
Furthermore, when the driving control state is in the A: OFF state,
if the driver depresses the control start switch 26 when the
vehicle 1 is stopped and when no preceding vehicle is detected by
the radar apparatus 11, the control state determination device 17
transitions the driving control state directly from the A: OFF
state to the C: STOP HOLD state (state transition SE10).
Furthermore, when the driving control state is in the C: STOP HOLD
state, if a preceding vehicle is detected by the radar apparatus 11
within a predetermined time counted by a timer (e.g., 1 second)
after the driver depresses the start/stop switch 26, the control
state determination device 17 transitions the driving control state
from the C: STOP HOLD state to the B: FOLLOW-UP state (state
transition SE11).
FIG. 5 is a flowchart showing an operation to determine whether to
start an LSF of the follow-up driving control. As shown in FIG. 5,
after an LSF start determination processing is started in step S1,
it is determined whether or not a start of an LSF is requested in
step S2. This can be made by determining whether or not the driver
depresses the control start switch 26. When the determination is
evaluated as "YES" in step S2, the flow proceeds to step S3.
Otherwise, if the decision made in step S2 is "NO", the processing
of this flowchart is terminated and the process in S1 is repeated
again.
In step S3, it is determined whether or not the vehicle speed of
the vehicle 1 detected by the vehicle speed sensor 3 is equal to or
less than a predetermined speed (for example, 40 km/h). When the
determination is evaluated as "YES," the flow proceeds to step S4.
Otherwise, if the decision made in step S3 is "NO", the processing
of this flowchart is terminated and the process in S1 is repeated
again. The reason this determination is made is that the LSF
control is a control to be executed when the vehicle 1 is driving
at a low speed. It should be noted that the above-described speed
to be used in the determination may be changed to any speed with
which a low speed can be determined.
In step S4, it is determined whether or not a preceding vehicle is
detected by the radar apparatus 11. When this determination is
evaluated as "YES," the flow proceeds to step S5. Otherwise, when
the determination is evaluated as NO, the flow moves to step S6. In
step S5, an LSF control is started. In this case, the driving state
of the vehicle transitions to the B: FOLLOW-UP state in which the
vehicle 1 is made to travel following the detected preceding
vehicle. Alternatively, when the detected preceding vehicle is
stopped, the state transitions to the C: STOP HOLD state. Then, the
processing of this flowchart is terminated and the process in S1 is
repeated again.
In step S6, it is determined whether or not the vehicle 1 is
stopped based on the vehicle speed of the vehicle 1 detected by the
vehicle speed sensor 3. When this determination is evaluated as
"YES," the flow proceeds to step S7. Otherwise, if the decision
made in step S5 is "NO", the processing of this flowchart is
terminated and the process in S1 is repeated again. In step S7, an
LSF control is started. In this case, the driving state of the
vehicle is in the C: STOP HOLD state. Then, the processing of this
flowchart is terminated and the process in S1 is repeated
again.
The operation of the above-described flowchart is repeated at a
predetermined interval (for example, 100 milliseconds).
Accordingly, after the driving control state is set to the C: STOP
HOLD state in step S7 because no preceding vehicle is detected, if
a preceding vehicle is detected within a predetermined time counted
by a timer (e.g., 1 second) in step S4 after the start/stop switch
26 is depressed by the driver in step S2, it is possible to
transition the driving state of the vehicle to the B: FOLLOW-UP
state in step S5.
As described previously, in the follow-up driving control apparatus
according to this embodiment, even when no preceding vehicle is
detected by the radar apparatus 11, a stop hold control is executed
by the brake control device 14 or the like when the vehicle 1 is
substantially stopped and when an intention of the driver to start
the control using the control start switch 26 is detected. As a
result, a stop hold control of the vehicle 1 can be executed even
when no preceding vehicle is detected by the radar apparatus 11
within a small distance. Accordingly, it is possible to maintain
the vehicle 1 in the stopped state even when the driver stops
operating the brake pedal. Furthermore, the discomfort that the
driver may feel when a follow-up control is cancelled even when the
preceding vehicle is present in front of the vehicle 1 is
eliminated.
Furthermore, when an intention by the driver to start the control
by means of the control start switch 26 is detected after the
preceding vehicle has started and the preceding vehicle can be
detected by the radar apparatus 11, the follow-up control in which
the vehicle is made to travel following the preceding vehicle is
executed by the throttle control device 13 or the like. Thus, it is
possible to smoothly switch a control mode to one in which the
vehicle 1 is made to travel following the preceding vehicle thereby
reducing the driver's load in carrying out driving operations. As
described herein, the term "a vehicle is substantially stopped"
means that the vehicle may be completely stopped, or the vehicle is
traveling at a speed at which the vehicle can be regarded as being
stopped (for example, at several kilometers per hour or less).
As described previously, according to the present invention, it is
possible to start an LSF control even when no preceding vehicle is
detected in front of the vehicle, thereby enhancing the
convenience.
It should be noted that the present invention is not limited to the
particular embodiment described above. For example, although the
above embodiment is explained using a follow-up control apparatus
having the radar apparatus 11 employing millimeter-waves, the radar
apparatus may use a different wavelength.
While preferred embodiments of the invention have been described
and illustrated above, it should be understood that these are
examples of the invention and are not to be considered as limiting.
Additions, omissions, substitutions, and other modifications can be
made without departing from the spirit or scope of the present
invention. Accordingly, the invention is not to be considered as
being limited by the foregoing description, and is only limited by
the scope of the appended claims.
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